1. Field of the Invention
The present invention pertains to a method for detecting HMGI-C or HMGI(Y) as a diagnostic marker for benign or malignant tumors using a probe for a sample from a patient that recognizes HMGI-C or HMGI(Y). The method comprises the steps of (a) contacting HMGI-C or HMGI(Y) from a sample from a patient with a probe which binds to HMGI-C or HMGI(Y); and (b) analyzing for HMGI-C or HMGI(Y) by detecting levels of the probe bound to the HMGI-C or HMGI(Y). The presence of HMGI-C or HMGI(Y) in the sample is positive for a benign or malignant tumor. The present invention also pertains to a method for detecting antibodies to HMGI-C or HMGI(Y) as a diagnostic marker for benign or malignant tumors. The present invention further pertains to a method for treating benign and malignant tumors in a patient by blocking the biological activity of HMGI-C or HMGI(Y). The present invention also pertains to a method for treating obesity in a patient by blocking the biological activity of HMGI-C or HMGI(Y).
2. Description of the Background
The disclosures referred to herein to illustrate the background of the invention and to provide additional detail with respect to its practice are incorporated herein by reference and, for convenience, are referenced in the following text and respectively grouped in the appended bibliography.
HMGI Proteins in Adipogenesis and Mesenchyme Differentiation Understanding various genes and pathways underlying development of multicellular organisms provide insights into the molecular basis of the highly regulated processes of cellular proliferation and differentiation. In turn, genetic aberrations in control of cell growth lead to a variety of developmental abnormalities and, most prominently, cancer (Aaronson, 1991). To pursue identification of genes involved in these fundamental biological processes, the viable pygmy mutation (MacArthur, 1944) was investigated because it gives rise to mice of small stature due to a disruption in overall growth and development of the mouse. An insertional transgenic mutant facilitated cloning of the locus (Xiang et al., 1990) and subsequently it was shown that expression of the HMGI-C gene was abrogated in three pygmy alleles (unpublished results).
HMGI-C belongs to the HMG (high mobility group) family of DNA-binding proteins which are abundant, heterogeneous, non-histone components of chromatin (Grosschedl et al., 1994). HMG proteins are divided into three distinct families, the HMG box-containing HMG1/2, the active chromatin associated HMG14/17 and the HMGI proteins (Grosschedl et al., 1994). At present, the last family consists of two genes, HMGI(Y) (Johnson et al., 1988; Friedmann et al., 1993) which produces two proteins via alternative splicing (Johnson et al., 1989) and HMGI-C (Manfioletti et al., 1991; Patel et al., 1994). A prominent feature of HMGI proteins is the presence of DNA-binding domains which bind to the narrow minor groove of A-T rich DNA (Reeves and Nissen, 1990) and are therefore referred to as A-T hooks. Recently, valuable insights have been gained into their mechanism and role in transcription (Thanos and Maniatis, 1992; Du et al., 1993). The HMGI proteins have no transcriptional activity per se (Wolffe, 1994), but through protein-protein and protein-DNA interactions organize the framework of the nucleoprotein-DNA transcriptional complex. This framework is attained by their ability to change the conformation of DNA and these proteins are therefore termed architectural factors (Wolffe, 1994). In the well-studied case of HMGI(Y) and the interferon B promoter, HMGI(Y) stimulates binding of NF-KB and ATF-2 to appropriate sequences and alters the DNA structure which allows the two factors to interact with each other and presumably with the basal transcription machinery (Thanos and Maniatis, 1992; Du et al., 1993).
A number of studies have revealed an association between increased expression levels of HMGI proteins and transformation (Giancotti et al., 1987, 1989, 1993). For example, in chemically, virally or spontaneously derived tumors, appreciable expression of HMGI-C was found in contrast to no detectable expression in normal tissues or untransformed cells (Giancotti et al., 1989). A recent study has demonstrated a more direct role for HMGI-C in transformation (Berlingieri et al., 1995). Cells infected with oncogenic retroviruses failed to exhibit various phenotypic markers of transformation if HMGI-C protein synthesis was specifically inhibited.
DNA probes adjacent to HMGI-C were mapped to the distal portion of mouse chromosome 10 in a region syntenic to the long arm of human chromosome 12 including and distal to band q13 (Justice et al., 1990). This genomic region is under intensive investigation because it is the location of consistent rearrangements in a number of neoplasms, mainly of mesenchymal origin (Schoenberg Fejzo et al., 1995). Lipomas, tumors mainly composed of mature fat cells, are one of the most common mesenchymal neoplasms that occur in humans (Sreekantaiah et al., 1991). Approximately 50% of lipomas are characterized by cytogenetic rearrangements and the predominant alteration is a presumably balanced translocation involving 12q14-15 with a large variety of chromosomal partners including 1,2,3,4,5,6,7,10,11,13,15,17,21, and X (Sreekantaiah et al., 1991; Fletcher et al., 1993). This variability in reciprocal translocations along with duplications, inversions, and deletions of 12q14-15 in these tumors, strongly indicates a primary role of a gene on chromosome 12 in lipomas. Furthermore, this gene may play a key role in normal differentiation of primitive mesenchyme as not only lipomas, but also uterine leiomyomas (smooth muscle tumors), lipoleiomyomas (smooth muscle and adipose components), and pulmonary chondroid hamartomas (primitive mesenchyme, smooth muscle, adipose, and mature cartilage components) are all clonal proliferations that are characterized by rearrangements of 12q14-15 (Schoenberg Fejzo et al., 1995).
Interestingly, breakpoints in a lipoma, a pulmonary chondroid hamartoma and uterine leiomyomata have been shown to map within a single YAC (Schoenberg Fejzo et al., 1995).